Stents and stent delivery assemblies are utilized in a number of medical procedures and situations, and as such their structure and function are well known. A stent is a generally cylindrical prosthesis introduced via a catheter into a lumen of a body vessel in a configuration having a generally reduced diameter and then expanded to the diameter of the vessel. In its expanded configuration, the stent supports and reinforces the vessel walls while maintaining the vessel in an open, unobstructed condition.
Stents are available in both self-expanding and inflation or balloon expandable configurations. Inflation expandable stents are well known and widely available in a variety of designs and configurations. Both self-expanding and inflation expandable stents are typically crimped to their reduced configuration after being disposed about a delivery catheter. They are maneuvered to the deployment site and expanded to the vessel diameter either by fluid inflation of a balloon positioned between the stent and the delivery catheter, or upon release of the self-expanding stent from its crimped state, typically from a retaining sleeve.
Stents that are not properly secured or retained to the catheter may slip and either be lost or be deployed in the wrong location or partially deployed. Therefore, it is important that they be properly secured to or retained on or about the catheter. In securing a stent to a catheter, however, the stent must be crimped in such a way as to minimize or prevent altogether distortion of the stent and to thereby prevent abrasion and/or reduce trauma of the vessel walls.
Devices for reducing the diameter of stents are generally known, such as described in U.S. Pat. No. 6,360,577 to Austin, the entire disclosure of which is incorporated herein by reference.
Self-expanding stents offer some unique challenges when being loaded on a catheter in part because they have a tendency to open of their own volition at ambient conditions. Thus, it is common practice when loading a self-expanding stent onto a catheter, to constrain only one half of the length of a strut at one time. This is more time and labor intensive because it requires reducing the diameter of the stent a little bit of the stent at a time.
It would be desirable to be able to crimp a stent in sections of varying diameter depending on how one would desire the stent to deploy.
There remains a need in the art for a crimping device that provides more flexibility during the crimping process.